Management of Disseminated Superficial Actinic Porokeratosis (DSAP)
The management of disseminated superficial actinic porokeratosis (DSAP) should focus on UV protection as the foundation, with field-directed therapies like 5-fluorouracil or imiquimod for multiple lesions, and lesion-directed approaches like cryosurgery for isolated lesions. 1
Understanding DSAP
DSAP is a chronic disorder of keratinization characterized by:
- Multiple small, brown plaques with elevated keratotic rims
- Typically occurs on sun-exposed areas
- Female predominance
- Usually manifests in third or fourth decades
- Carries risk of malignant transformation
Treatment Algorithm
Step 1: UV Protection (Essential for All Patients)
- Strict sun protection measures to prevent new lesions and progression of existing ones 1
- Daily use of broad-spectrum sunscreens
- Protective clothing
- Sun avoidance during peak hours
Step 2: Select Treatment Based on Lesion Number and Characteristics
For Low Number of Lesions:
- Cryosurgery: First-line for isolated lesions, particularly effective on face, scalp, and ears 1
- Curettage: For hypertrophic or resistant isolated lesions 1
For High Number of Lesions:
- Topical 5-fluorouracil (5-FU): 0.5% cream once daily for 1-4 weeks, particularly effective on scalp, face, and hands 1
- Topical imiquimod: 5% cream 2-3 times weekly for 4-16 weeks, or 2.5%/3.75% cream daily for 2-3 weeks on/off cycles 1
- Diclofenac gel 3%: Moderate efficacy with good tolerability, better suited for lesions below the knee 1, 2
For Treatment-Resistant Cases:
- Chemical peels: Using glycolic acid 50% and salicylic acid 25% in a two-layer technique, repeated approximately every 6 weeks 3
- Calcipotriol/betamethasone gel: Has shown promising results in treatment-resistant cases 4
Treatment Selection Based on Location
| Location | Preferred Treatment |
|---|---|
| Face, scalp, ears | Cryosurgery, 5-FU, imiquimod |
| Periorbital | Cryosurgery, curettage (avoid topicals) |
| Confluent scalp | 5-FU, imiquimod (consider pre-treatment with 5% salicylic acid) |
| Below knee | Curettage, cryosurgery, diclofenac |
| Hands | Cryosurgery, 5-FU |
Important Clinical Considerations
Regular follow-up is essential due to:
- Chronic, relapsing nature of DSAP
- Risk of malignant transformation
- Need to assess treatment response 1
Biopsy indications:
- Diagnostic uncertainty
- Failure to respond to appropriate therapy
- Lesions with concerning features (rapid growth, ulceration, bleeding) 1
Treatment challenges:
Clinical Pearls and Pitfalls
- Pearl: Pre-treatment with 5% salicylic acid can improve penetration of topical agents in hyperkeratotic lesions 1
- Pitfall: DSAP is often misdiagnosed as chronic UV damage or actinic keratoses, leading to years of ineffective treatment 3
- Pearl: Chemical peels can be effective for refractory cases that have failed conventional treatments 3
- Pitfall: Avoid topical treatments in periorbital areas due to risk of irritation 1
- Pearl: A systematic approach based on lesion number, thickness, and location leads to better outcomes 1